The present disclosure generally relates to anthrapyridone compounds. These anthrapyridone compounds are useful as thermally stable colorants in polymer compositions.
Colored polymer compositions are generally prepared by incorporating a colorant material in the polymer composition using processing techniques, such as extrusion or molding. The method of incorporating the colorant material depends upon, among other conditions, the nature of the polymer. For polymers that require high processing temperatures, for example greater than or equal to about 350° C., the colorant material should be thermally stable during the processing step. Examples of polymers that require such high processing temperatures include high heat polymers that have a glass transition temperature greater than that of bisphenol A homopolycarbonate. For example, polyetherimides such as ULTEM™ polyetherimide are examples of high heat polymers. Further, the colored polymer compositions so produced sometimes exhibit a color shift or a color that is different from the observed color of the colorant before it is included in the polymer compositions. The color shift is believed to occur due to the thermal instability of the colorant material. Additionally, the colorant materials in the colored polymer compositions can undergo degradation due to natural weathering, caused in part by sunlight, humidity, temperature, and the like.
Therefore there is a need for colorants that are resistant to thermal degradation, have good weatherability, and show little or no color shift when processed with polymers at elevated temperatures.